1. Field of the Invention
This invention relates to an apparatus for assembling a magnetic disk cartridge and a method of producing the same. More specifically, the invention relates to an assembling apparatus for continuously moving a shell together with a liner placed on the shell and for welding (fusingly bonding) the liner to the shell by an ultrasonic welding device, and to a production method using this assembling apparatus.
2. Description of the Prior Art
For the purposes of easy handling and protection from dust, a disk-shaped recording medium, such as a magnetic disk, is conventionally housed in a relatively rigid cartridge case and loaded, together with this case, into a recording and reproducing device so as to record and reproduce desired information.
For example, as shown in FIG. 4, a 3.5-inch micro-floppy disk is widely used for such a magnetic disk cartridge. A magnetic disk cartridge 1 includes liners 9 and 10 secured respectively to inner surfaces of upper and lower half shells 2 and 3 which are of a rectangular shape and molded of an ABS resin or the like. A magnetic disk 5 is rotatably interposed between the liners 9 and 10. The magnetic disk 5 is a flexible magnetic recording medium which comprises a polymeric film substrate of a disk-shape having a magnetic layer uniformly formed on a surface thereof. A ring-shaped center core 4 is fixed to a circular opening formed through the central portion of the magnetic disk 5. Formed through the central portion of lower half shell 3 is a opening 7 through which a motor shaft (not shown) is adapted to be inserted in a motor shaft insertion hole 4a of a generally square shape formed in the center core 4. Formed through each of upper and lower half shells 2 and 3 is a magnetic head insertion opening 8 into which a magnetic head (not shown) for writing and reading required information signals relative to the magnetic disk 5, as well as a magnetic pad, is adapted to be inserted.
Although not shown, a slide-type shutter for opening and closing the magnetic head insertion openings 8 is slidably mounted on a stepped portions 8a surrounding the openings 8, so that the shutter can protect the disk 5 and prevent dust from damaging the disk 5.
Usually, the liners 9 and 10 are welded to the half shells 2 and 3 using an assembling apparatus 105 as shown in FIG. 5. The assembling apparatus 105, has a conveyance system having, for example, a conveyor 108, and guide members 106 and 107 which guide the conveyor 108 and support the half shell 2 or 3 from below. This conveyance system intermittently conveys the half shell 2 or 3 in a predetermined direction. An ultrasonic welding device is provided at a predetermined position, and a welding horn head 110 of this ultrasonic welding device presses the liner 9 or 10 against the half shell 2 or 3 from above. The assembling apparatus 105 welds the assemblies (each composed of the half shell and the liner), fed one after another by the conveyor 108, and conveys them to the next assembling step.
In such a conventional welding process, a relatively large amount of dust, such as powder of the resin of the half shell and the fibers of the liner, is produced by ultrasonic vibrations. Therefore, the dust is drawn by a suitable means, and for example, as shown in FIG. 5, the dust is drawn from exhaust hoods 111 which are provided on the upper surfaces of guide members 106 and 107 and are disposed close to the welding horn head 110. Naturally, this exhaust system includes pipes 112, a exhaust pump 114, a filter 113, as well as other components.
However, most of the above-mentioned dust is fibrous dust produced from the liners 9 and 10. In addition, static electricity is produced by the contact between the welding horn head 110 and the assemblies (the half shell and the liner), the contact between the half shell 9 or 10 and the conveyor 108, the sliding contact between the conveyor 108 and the guide members 106 and 107, and other moving contact of the device. Thusly, the welding horn head 110, guide members 106 and 107 and the surrounding parts are statically charged. As a result, at those places where the force due to static electricity is stronger than the suction force of the exhaust hoods 111, the fibrous dust remains adhered to such places and eventually accumulates into large wooly deposits. These large wooly deposits of dust will eventually drop due to vibrations resulting from the driving of the apparatus 105. Such a large lump of dust is likely to become clogged in the pipe 112 of the exhaust system, or become lodged in slits or small holes formed in a cover when such a cover is provided on the exhaust hood 111, thus causing various problems. Also, if such deposits of dust intrude in between the conveyance system and the half shell, the half shell 2 or 3 may not be conveyed properly, thus causing problems in the manufacturing of the disk cartridge 1.
Further, if such deposits of dust fall and deposit on the inner surface of the half shell 2, 3, it would adversely affect the recording and reproducing function of the magnetic disk cartridge 1. Therefore, the assembling apparatus 105 must be frequently cleaned, and this maintenance is laborious. In addition, each time the maintenance is carried out, the assembling apparatus 105 must be stopped, which lowers productivity.
In view of the foregoing, it may be considered advisable to enhance the suction ability of the exhaust hood 111. However, if the suction force is increased, the liners 9, 10 are often displaced out of position by this suction force, so that proper welding cannot be accomplished.